The webmail and cPanel interfaces use the server wide certificate installed in the service SSL certificates section of WHM. Currently there is no supported way of installing per domain certificates for the webmail interface. You might like to vote on the feature request for this functionality

Staff Member

There's no difference when it comes to security, but that warning message will appear until a user chooses to trust the certificate with their browser. It will also display that domain name to anyone who accesses that service securely.

Staff Member

That is correct. There is no difference in speed or performance. It's simply a warning message telling you (or anyone else) that the certificate does not match and the user should be careful before continuing. That's all.